Many clinical examples exist which require the use of a high-precision technology to eradicate tumors that are located next to vital anatomical sites. Sites that are often inaccessible or unsafe for treatment by traditional surgical and medical methods include major blood vessels such as the carotid arteries, critical areas of the brain, and portions of the eye. We will develop a site-specific fiber optic-based singlet oxygen generator, which has the potential to be used as a precise photochemical surgical knife to destroy tumor cells in areas that require cytotoxic control and are inaccessible by surgical methods. A fiber optic-based singlet oxygen generator for targeted singlet oxygen delivery is proposed for use in photodynamic therapy and drug delivery. The objective is to design a heterogeneous photodynamic therapy device that uses the optical excitation of sensitizer molecules released from porous ends on hollow photonic band-gap optical fibers through which O2 flows. The proposed research is predicated upon our strong preliminary data showing that porous Vycor glass serves as a photosensitizer support and can be integrated to a hollow fiber optic that is effective in generating singlet oxygen in aqueous solution. The hypothesis is that sensitizer molecules released from the fiber optic device will be localized at a tumor site and that high concentrations of singlet oxygen will be produced for its destruction at that site. This project is innovative in that, to date, all photodynamic therapy strategies have involved the systemic administration of a sensitizer; our work would therefore be the first to cleave a photosensitizer from the end of a fiber optic device through which O2 flows. The improved singlet oxygen delivery and selectivity is expected to fill a new niche in preclinical photodynamic therapy.